Echo elongator



v May 19, 1959 B'. FANKEL ETAL EcHo ELgmGAToR Filed Maren 18, 1957 mumm @acumul- INVENTOR. BURTON FRANKEL By FREDERICK B CUPP Unite v1 ECHO ELoNGA'roR Burton Frankel, South Euclid, and Frederick B. Cupp, Cleveland, Ohio, assignors to Clevite Corporation, Cleveland, Ohio, a corporation of Ohio Application March 18, 1957, Serial No.`646,930 l 7 Claims. (C1. 340-3) "This invention pertains to a sonar device used inthe trai-ning of sonar operators to acquaint them with the eharacteristicsounds of a sonar pingvreturning from a submarine.

It is essential that sonar operators recognize the re- !llected sonar ping from a submarine and that they dis-` and it ties up a large number of submarines which are needed for other. tasks.

.In order to train sonar operators without tying up submarines, a submarine simulator has been devised which can .be maneuvered in accordance with a built-in program.. The unmanned submarine simulator is quite small compared to a standard size submarine, and Ibecause of. this, if a sonar reection is picked up from this small" sized hull it will not be characteristic -of -a standard size submarine. f

-An object of the present inventionis to provide a.l

small, unmanned submarine simulator which sends a signalback to. a sonar operator which is characteristicV of Ia reilected signal from a full-size submarine.

yIt is an object of the present .invention to provide a small submarine simulator which can. receive'a sonar ping and send a return signal to the sonar operator which in amplitude, frequency and duration is characteristic of a reected sonar signal from a full-size submarine. l

A further object of this invention is to provide a sonar training device which, while it is` quite small, sounds like a lreilection from a full-size submarine to the sona operator.

For a better understanding ofr the present invention,

together with other and further objects thereof,l reference is had to the following. description takenin connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

An object of the present invention lies in the provisionj of a sonar device which preferably is in the form of an elongated, torpedo-like hull which can travel under water. The device has two spaced-apart receiving transducers, preferably mounted one on the bow and the other aft for receivin-g sonar pings. Within this hull are means for comparing the time relationship of the sonar pings as received by the forward and aft transducers. Signal generating means are located within the hullA of the device and are connected to the comparing means for generating a signal having a characteristic which is a function of the time relationship, and transmitting transducer means are mounted on the hull of the device and are connected to they signal generating means for transmitting thegenerated signal away from the hull.

AStates Patent dice azri Patented May 1?;'71959 With reference to the single sheet of drawing there is shown in Figure l a schematic view of the submarine simulator and an 'approaching sonarwave front.

Figure 2 is a block diagram of the circuit of the sub marine simulator.

With reference to Figure l there is shown afsniall submarine simulator 10 having a propeller and-rudder system for driving and guiding it underwater. Within the -hull which is very small compared to a submarine there is a propulsion plant and a system for putting the simulator 10` through a program of turning :and diving operations. The simulator has a bow transducer 15 and an aft transducer 16 which is spaced away from the bow transducer 15.

.The 4wave-front of an incoming sonar ping is shown at 17, and is illustrated as a plane wave-front `due to the distance to the sonar source. This wave-front may approach the simulator 10 from att, abeam or from theVA bow, and the system to lbe described will operate equally well. -It is the business of this little simulator, which 'is' f only l0ffeet long, to sound like a 300 or- 400'- submarine to the sonar operator located at a distance` away from the simulator. Thus the signal which it sends-back tolt'he sonar operator must, in amplitudeand induration, tbe" equivalent to the reflection from a submarine which'is say, 40 in diameter and 400 long. Furthermore, the reected signal from vthe simulatormust sound like avsubmarine for all angular relationships between the sonar source and the simulator. To do this the simula` torvrepeats/v the incoming signal, sending it back'to vthe sonaroperator with amplification, and it elongates the echo by an amount which is a'function ofthe size of' thefsubmarine which the device is`simu1ating and lby an amount dependent upon the angle between the/wave?" front 17 and the longitudinal axis of the hullofVthe simulator 10. The less this angle, down to zero degrees," the shorter the echo, and at zero `degrees the echo' length is approximately equal in'length to thatof"`the received sonar ping. `f The echo repeater circuit operates inA conjunction'` with the bow transducer 15, which receives the-inc`om ing sonar ping, -ampliiies it at 18 and againat-'fthelz recording amplifier 19, and applies the signal to the input of a magnetic recording head 20. The magnetic recording head 20 records the signal on the rapidly rotating' magnetic wheel 21. The diameter of the wheel 21 is small f and its rate of rotation is suiciently high that the re' corded signal occupies the full 360 -degree `path around the wheel. If the ping is long and occupies more thanE 360 degrees of rotation it does not disturb the operationVr ofthe device. j When the signal magnetically recorded on' wheel' 215:' reaches-reproducing head 22 it is reproduced, ampli'edv atv23` and'24 and through switch 25 is appliedV to the aft"` transducer 16 where it 'is sent back to the sonar 'operatorf in the form of an amplified echo, strong"enoughto` -4 have been reflected from a large submarine. v The elongater circuit `computes the duration 'of ther" echo in accordance with' the size of the submarin,f the length of the ping; and in accordance witlithe'aspect'- angle between the wave-front 17 and the airis of thel simulator l0. The size of the submarine isiixed, but the aspect angle varies during the training exercise and the, length of the ping may vary. il. .When the wave-front 17 approaches from abeam, the aft and ybow transducers receive the impulse simultaneq ously and the arrival time diterence of; the two trans-.f

ducers will be zero. However, at bow or stern aspects the arrival time diiterence may reach a maximum 011;V

about '.9 millisecond because of the hydrophonesp'acing L of about live feet and the speed of sound in Water. With on the magnetic wheel 21 following each` transmission period.4

When a. sonar` ping is rst received by the aft transducerl, thetransducer output is amplified at 26 limited at 27,4 rectified at` 2S and used to start a Hip-flop circuit` 29.` Theoutputfromthe lijp-:Bop is applied to a coincidence detectoncircuit whose output isrecticd by rectiier 31 and stored for a short period of time in a signal storage` circuit 32. Subsequently the ping is received by the bow transducer whose output is amplified at 18` andlimitedby,limiter 33. Here the output issplit, part being appliedto rectier 34 and then to` the. pulse addition circuit-,35, limiter. 33 isrectiiied at rectifier 36 and is then` applied to` a flip-tipp, circuit 37 to terminate the` action of the..

coincidence .i detector circuit 30. The output of thecoincidencemdetectorcircuit 30 is rectiiied at 31 and stored ins-32.

`Either .hydrophone can start` the action of the` coin-f cidenef; detector circuit upon rst receiving the sonar ping, and the other hydrophone thenterrninates the action-ot thecoincidence detector circuit, the flip-op circuitsanl` the coincidence detector producing a signal whoseidurationis dependent upon the time delay between theA two hydrophones 15 and 16 receiving the sonar ping.

This .signal A:is ,stored inthe signal storage device 32,Y

and in the pulseaddition circuit 35 is added to the sonar pingjas received by the bow transducers 15. Thus,

out of thepulse addition circuit 35 there will be sent-a` Signat-whose duration is equal to the ,time `intervalfof i thepriginal sonar ping as received by transducer 15 plus aftirneinterval` dependent upon the receipt `of the ping at the two hydrophones 15, 16.

`:'Ilztewfront of the elongated signal derived from the..

pulseadded 35 is applied, after shaping at 40, tothe erase switch41jshutting off the erase current to the erase headp22,convertingfhead V22 to a reproducing head and supplying thereproduced signal from wheel `21,` through amplifiers, 23,` 24 and switch 25 to the output transducer 1d ,untilA theendofthe elongated signalout of the circuit 35:,returns the reproducing head 22 to an erase head by Y actuating switch/41,` Thus the signalrecorded on the magnetic `wheel) 21 is reproduced. for alength of time equal l to theY length oftime `of the. sonar ping plus the,

tirrre-delayrl between jthe rst and second transducers receiving, the sonar ping.V VDuring this time the wheel 21 may rotate several complete revolutions while vits repro.

ducedsignalis being sent backtowthe sonar operator, thus a 4large size submarine. The 4frequency of nal returned tothe sonar operator will be thesame g as. the, .incominglsonar signal since` the signal was re-r..

, `60 duced HtherefromLandyapplied to the aft transducer for corded..fdirectly` on the magnetic wheel and wasrepro-` transmittalbacldto the sonar operator. It is within vthe scopefofthils invention to` use a transmitting transducer which is `,independentfofeither of the two receiving trans- Whemthe systemV within the submarine simulator is at r renst, tliat is,j. no sonar, ping is actually beingreceived `or transmitted, the magnetic wheel 21 ris runningand both of the transducers 15, 16 are receiving random noise. 'I'lruandoni' noise received `by. the bow transducer `15.

The `other part of thel signal fromthe 4, signal from the ip-flop circuit actuates the trigger circuit 38 and connects the recording amplier 19 to therecording head 20 for recording the sonar pulse on the magnetic wheel 21.

A muting circuit 39 is connected in parallel with the reproducing head 22 between the erase switch 41 and the transmitting amplifier 23.2 While the system is listening for a sonar ping the muting circuit operates to inactivate the amplifier 23 thus preventing the aft transducerl fromcontinually transmitting amplified` noise` signals,` UponitheLreceipt of an incoming sonar signal the erase switch 41qinactivates the mute circuib39, thereby putting` amplifier 23 in operatingcondition to` amplify the signalreproducedfrom the magnetic wheel 21, and when the signal transmittingcircuit has `finished sending out the amplified sonar signal the muting circuit 39 returns ampliiier 23 to its quiet condition.

WhileI there have been described what are at present l' consideredto be the preferred embodiments of this inis lnot"imagnetically recorded on thewheel 21 Asince the record ampliiier 19 is maintained. in a non-transmitting state b'y'a re'cr'dltrigger circuit 38#4 When a sonar ping offa 'given' amplitude, Agreat compared to the ambient noise'isreceived"by`the bow transducer 15` an output vention, it will` be obvious to those-skilledin-the art that various changes* and=modications` may be Vmade thereinAJ without departing from the invention, and it is, therefore; aimed in thetappendedfclaims to cover `all such changes and-modifications as fall within `the true spirit and scope ofthe-invention.

1'.h Inrasonardevice, an elongated hull'to be placedl underwater-,and having -a -forward and Aan aft transducer fo1fre `:eivi`ngl a sonar ping, comparing meanslmountedfin' said bullion-comparing thetime relationship of arrivalofagi'ven pingas received by said forward and afttrans-I ducers,l means Vconnecting said forward'andaft trans--1 ducers toi said comparing means, signal generating meansconnectedto-said c'omparingmeans for generatinga signal* having a characteristic which is a-function of saidlrela-r tionship`,.` and transmitting t transducer means mounted on-said `elongated hull andconnected to said signal gen-rr eratingmeansl forntransmitting said generated signal.

' 22 Arsonar-device-as setlforthinclaim 1, further chart acier-ized by said transmitting transducer means comprising onelof said forward and aft transducers.

f3. In -a sonar device,` anrelongated hull to beplacedt underwater and having a forward and an afttransducerfor receiving ralrsonarwping, comparing means -mounted ini-said `hulljfor` comparing the time of arrival relation-- shipwofwthe pingM as :received by-said forward andA aftff transducers,means connecting said forward and aft transducers to said comparing means, signal generating means connected to said comparing means for generating a signals whose duration is'rafunction of said comparison,` and transmitting transducer means mounted on saidfelon-wt gated hull and connected to said signal generating means for* transmitting said generated signal.

4L'In: a sonar device, an elongated hull to be placed i underwater andfhaving a forward and an aft` transducer for receiving a sonar ping, comparing means mountedf innsaidhull `for comparing the time of arrival relation ship-vof `the ping as 'received1 by` said forward and aft1 transducers, means `connecting fsaidifforward and `atti transducersto said ycomparing means; signal recordingl means connected to one of4 said transducers `for record ing `said. sonar ping,` `signal reproducing means associated with lsaidt signal recording means and controlled by said comparing meansj forlgenerating` a signal whose duration i isa function ofsaid comparison, and transmitting transducer means mounted on-` said elongated hull andbcon-V nected to saidsignal reproducing meansfor transmitting said generated signal.

5.11m a sonar device, ahulllto be placed underwater 1 andlhaving spaced apart transducers for receivingfa sonar f ping-comparing meansmounted insaid hull for-com-` paring the time ofarrival relationship Yof. the" -ping as W received by said two` transducers, means connecting said i twotransducers -to said comparing means, signal record--l ing` meansmounted within said hull and` electrically4 connected to said transducers for recording a signal thereon, reproducing means associated with said signal recording means for reproducing the recorded signal therefrom, means connecting said reproducing means to one of said transducers for transmitting the reproduced signal away from said hull, and signal erasing means associated with said signal recording means and electrically connected to said comparing means to control the erasing of the signal recorded thereon in accordance with the relationship of the signals received by said two spaced apart transducers.

6. A sonar device as set forth in claim 5, further characterized by said signal recording means comprising a magnetic recording device.

7. In a sonar device, a hull to =be placed underwater and having spaced apart fore and aft transducers for receiving a sonar ping, endless magnetic recording means mounted within said hull and connected to one of said transducers for recording the signal picked up by said transducer, reproducing means `associated with said magnetic recording means for reproducing the signal therefrom, transmitting transducer means mounted on said hull and connected to said reproducing means for tran-smitting away from said Ihull the signal reproduced from,

References Cited in the file of this patent UNITED STATES PATENTS McMillan Nov. 23, 1954 

